Modified polyphenylene ether resins obtained using polyphenylene ether (hereinafter, also referred to simply as “PPE”) as a raw material can be used to produce products and components with desired shapes through molding methods such as melt-injection molding and melt-extrusion molding. Therefore, modified PPE resins are used as materials for products and components in various industrial material fields, such as in the electrical and electronic industry and the automotive industry.
In a known conventional method for producing PPE, a phenolic compound is subjected to oxidative polymerization in the presence of a metal catalyst and an amine in a good solvent for PPE. A method has also been proposed by which a PPE solution obtained through the aforementioned method is heated to evaporate the good solvent and concentrate PPE prior to isolation of PPE from the PPE solution. Moreover, according to a known method, a liquid containing a poor solvent for PPE is added to the PPE solution to precipitate PPE, which is then solid-liquid separated, washed with a poor solvent for PPE, and then solid-liquid separated once again (refer to PTL 1).